Instrument for measuring inside dimensions



Dec. Z9, 1953 H. RUDOLPH INSTRUMENT FOR MEASURING INSIDE DIMEN SIONS Filed Nov. 24, 1952 Patented Dec. 29, k1953 UNITED STATES PATENT QFFIQCE INSTRUMENT Fon MEASURLNG INSIDE.

' DIMENSIONS` HansfRudolph, Kansas City, Mo. Application Novemberzi, 1952, serial No; 322,212

: Claims. (Cl. 3T3-#1.5640

This invention relates to high precision measuring instrumentsV andl more particularlyv to an instrument for taking inside measurements such as in holes, openings, grooves and the like,- the primaryV object being to improve upon devices of this class so as to render-'the same more accurate, simpler to manufacture and use, aswell as sturdy throughout.

It is the object of this inventionlto provide an inside gauge that includes a pair ofnovel gauge ,A

shaped cam for spreading the gauge elements,

there beingprovided a special holder `for the gauge elements having fingers provided with ay slideway to maintainr not only the gauge elements themselves, but the cam, in proper alignment and relationship at all times. Y

Other objects include the way in Which the cam is reciprocated by means of 'a screw having an anvil thereon bearing against a spring-loaded cam; the manner of providing an extension sleeve for receiving the screw, thejcam, and a micrometer tube; theway in which a thimble isy rotatably mounted on the micrometer tube and operably coupled with the screw; andmany more minor aims and objects, ally of which will be made clear as the following specification progresses.

In the drawing: l Fig. l is a side elevational View of an instrument for measuring inside dimensions madel pursuant to my present invention.

Fig. 2 is an enlarged longitudinal cross-sectione al viewY taken on line II-II of Fig.. 1. l

Fig. 3 is a perspective view of the'gauge ele"-A ments entirely removed kfrom the gauge'bo'dy.

Fig. 4 is a perspective view of the guide mem'- o ber entirely removed from, the gauge body'.

Fig. 5` is a cross-sectional viewtakenv online V-V of Fig. 2.

the faces 3B-thereofvin sliding Fig. 6 is a cross-sectional view taken on' line VI-'VI of'Fig. 2; and

y Fig. '7 is a cross-sectional view taken on line VII- VII of Fig. 2.

In the form of the invention chosen for' illusn tration there is included a' gauge body broadly designated by the numeral I 0 and including a hollow cylindrical portion I2 having the lowermost end thereof closed by a guide member I4 threaded thereinto. The'body I0 includesaddijtionaliy an elongated tubular ing from portion 52 oppositel-y to member- I4'.

A wedge-shaped cam lf3 reciprocable within the `body portion I2 has anelongated stem 2v2-extending through the tubular portion lr6', and a spring 22, coiled about the stem 2i) within the tubular portion I6, maintains the ably biased at one end of its path ofk travel as shown in Fig. 2 of the drawing. The tension on spring 22 is determined by a bushing 24y threaded on the stern 20 and serving as an abutment for one end of the springv 22. f

The guidey member slideway 26 which also separates a-pai-r oi'ngers- 28 and 30 forming a part of the guide member I4 and housed within the body portion I2.

The slideway 26 receives a pair oi L-shape'd gauge elements 32 and 34- for relative sliding movement toward yandV away from each other. Elements 32 and '34- are ident-ical and inelude'an elongated leg 32, a'fe'eler 36, an innermost face 33, a rabbet 40 and a tenon 42. Thenfaces 38 are relatively inclined complementally with cam I I8 and it isto be noted that theV innermost edge of the tenons 42 constitute cont-inuations of Vtheface 32. The'lowermost, bers 32 and 34', and accordingly of the triangular shaped tenon 42, restv upon the bottom wall ofk the slideway 26 in the guide member I-4.

The rabbets- 40 are complemental toand of the same size as the tenons 42 to the end that each tenon 42' ts within a rabbet 40 when the elements 32v and 34 are together. It is seen further that virtue of the overlapped joint' be# tween the elements 32 and 34,? tenons 42 are in interengagemont for relative sliding movement.

'Ifhe wedge cam I8V extends between the leg's'35` of elements 32 and 34 and bet-Ween the fingers 28 and 30 in the sldeway 26for spreading the elements 32 and 34 apart when the cam |18 is moved toward a clearance cavity 44Y therefor in the guidel member I4. Slideway 26, therefore, not only holds the elements 32 ment, but rest-rains the cam I6 against rotational for maintaining the elements 32 and "'34-yieldablyv biased toward each other t'o therebyv maintain engagement withV the inclined faces ofcam I'3. Such means com# prises a tubular, .resilient sleeve 46 telescoped around the ngers 28@r and *Siiv andlarou'nd" th`e"legs 35 of eIement-s s2l andl 31:;Y lvatur'all or syntheticy rubber or similar elasticvmaterial issuitablefor the sleeve 46.

An extension sleeve 48 that. includes a; plaircof threfiablyf connected se. .tions Fill: and. 5.2 has the section 52 thereof threaded on the tubular por:

tion I6 vof body IQ., anda nutdke enlargement 5,4,

portion- I 6 extend-f- I4 is sloted to present a flatiaces of thememand 34 to rectilinear move-- movement relative to the gauge elements 32an'daocaeee tted on the extension 52, aids in the manipulation of the gauge. Section 50 has an elongated screw 56 threaded thereinto which terminates in an anvil 58 that bears against the proximal end of stem 26 which in turn projects beyond the bushing 24.

Section 50 is provided with a spring collet end 6l) remote from section 52 upon which is threads ed a tightening not 62 for varying the tension of section B on the screw 56.

A micrometer tube 64 is tightly fitted on the section 50 and a tubular turning thimble 66 is rotatably telescoped over the tube 64. A frustop Y.

conical socket 6u in the thimble 66 receives a similarly-shaped head l on the screw member 56, and a knurled collar 'i2v circumscribes the thimble 66 between a knurled annulus 'it on the thimble 66 and a cap 'It overlapping the thimble 66. A screw 18, passing through the cap 'I6 and into the screw member 56, clamps the collar 'I2 to the thimble 66 and rigidly interconnects thimble 56 and screw member 56 by drawing the head 'I tightly into the socket 68.

Micrometer scales are provided on the thimble 66 and on the tube 64 take the form of circumferential graduations 86 on `thimble 56 and linear graduations 82 on the tube 64.

In use, collar l2, cap "I6, screw 18, thimble 86, and screw member 56 are rotated as a unit in one direction relative to the section 5e and the tube 64 to move the anvil 58 toward the body portion I2 and thereby shift the stem 26, as well as the cam I8, toward the cavity 4d against the action of sprngn22 until the feelers 36 come into engagement with the walls of an opening or the like to be measured. The size of the* opening is reiiected on the scale SIP-,82.

When the collar 'I2 is manipulated to retract the elements 32 and 34, vspring 22 operates to return the wedge member I8 to the position shown in Fig. 2, and the rubber sleeve 46 acts to retractthe elements 32' 'and 34 in the slides/ay as to the position shown in Figs. 1, 2, and 7. By virtue of the fact that the triangularly-shaped cam I8 is provided with a lpair of opposed fiat faces 84 and Beas shown in Figs. 5 and 6, it is held in sliding engagement with the faces 38 and with the fingers 28 and 30 at all times andcannot possibly become misaligned or out of adiustment. The instrument as shown is easily assembled and disassambled for repair, lubrication or replacement of parts. It may be inexpensively manufactured and is appreciably less complicated than instruments of this class now available in the field, such simplicity being made possible Without sacriiicing accuracy or high precision. It can be made in any size including microscopic dimensions with equal accuracy.

It can now also be appreciated that the construction of the gauge is such as to permit substitution of an indicator dial in lieu of the microscopic scale chosen for illustration. The specially formed gauge elements 32 and 34 are also well suited for modication to ments 32 and 34 for right angle movement relative to the wedge I8 presents a principle of operv ters Patent is:

1. In a gauge, a body having a hollow portion;

adapt the instrument for measuring pitch diameter inthreaded openings if desired. Finally, mounting of the elea guide member mounted on said portion of the body, said member having a pair of lingers extending into said portion of the body and provided with a slideway therebetween; a pair of L- shaped gauge elements in said slideway and movable toward and away from each other, said elements each having a feeler and an elongated leg, said legs being provided with relatively inclined, innermost faces; a reciprocable, Wedge-shaped cam in said portion of the body between said legs for forcing the elements apart when the cam is moved in one direction; and a resilient sleeve surrounding the fingers and the legs for yieldably holding the legs biased toward each other with said faces of the legs engaging the cam.

2. In a gauge as set forth in claim 1 wherein said cam has a pair of opposed, fiat faces, and wherein the cam extends into the slideway whereby the cam is held against rotational movement relative to the elements as the cam is reciprocated.

3. Ina gauge as set forth in claim l wherein said elements ars provided with inter-engaging, relatively slidable parts, presenting an overlap joint therebetween.

4. In a gauge as set forth in claim l wherein said elements are each provided with a rabbet and a tenon, presenting an overlap joint between the elements, the tenons being in interengaging relationship and relatively slidable as the elements move toward and away from each other.

5. In a gauge as set forth in claim i wherein said rabbets and said tenons are triangular and complementary, whereby the tenon of each element is ttable in the rabbet of the other element when the elements are together.

6. In a gauge as set forth in claim 4 wherein one edge of the tenons constitutes a continuation of said innermost face of the elements 7. In a gauge, a body having a hollow portion; a guide member mounted on said portion of the body, said member having a pair of iingers extending into said portion of the body and provided with a slideway therebetween; a pair of L-shaped gauge elements in said slideway and movable toward and away from each other, said elements each having a feeler and an elongated leg, said legs being provided with relatively inclined, innermost faces; a reciprocable, wedgeshaped cam in said portion of the body between said. legs for forcing the elements apart when the cam is moved in one direction; resilient means yieldably holding the legs biased toward each other with said faces of the legs engaging the cam; a stem on the cam reciprocably carried by the body; spring means for yieldably holding the cam and stem biased in the opposite direction; and a reciprocable anvil bearing against the stem for moving the stem and cam in said one direction against the action of said spring means.

8. In a gauge as set forth in claim 7 wherein is provided an extension sleeve on the body for receiving said anvil, there being a screw on the. anvil carried by the sleeve therewithin for reciprocating the anvil., s Y

9. In a gauge as set forth in claim 8 wherein is provided means on said sleeve for varying theV No references cited. 

